I'm planning on a fair amount of modification for SoG. One of the things my players cottoned onto early was that this was to do with the Whispering Tyrant (earlier than I would have liked, actually, but that's neither here nor there).
They have developed the idea that they are heading for a final confrontation with Tar-Baphon at the climax of the AP. I've gone out of my way to drop hints that taking on Tar-Baphon himself is way out of their league, but they're convinced that at the climax, there's going to be some sort of mass battle.
At first I was trying to figure out how to disavow them of this, but then I started to think: "Why not?". Izaark, the half-orc cavalier and Knight of Ozem has been gathering knights loyal to him, while Yeva, the Sczarni-linked ranger from Varisia has been pulling together all manner of strings with her contacts to hire mercenaries and the like, while Skaarlia, the dhampir inquisitor, has been organising the Pharasmin church to lend a hand. They managed to get a couple of werewolf tribes on-side, as well as numerous others.
So I'm going to give 'em what they want, and modify the final part of SoG to include a mass battle, where the "good" people of Ustalav are making a final stand to crush the Whispering Way once and for all. In theme, it's going to be a little like the end of "Return of the King", which I think is just cool.
This is a great AP and I like the switch at the last book I cant wait to run it